The 16-year-old who opened fire Thursday on his classmates at Saugus High School before shooting himself has died, the Los Angeles County Sheriffs Department said Friday.

Officials identified the teen as Nathaniel Tennosuke Berhow, a student at the Santa Clarita, California, school, The Associated Press reported.

Berhow died at the hospital at 3:30 p.m. Friday. His mother was reportedly with him at the time.

School security footage showed Berhow arriving on campus Thursday morning, removing a .45-caliber handgun from his backpack and shooting at five students in the quad. Berhow then shot himself in the head. The attack lasted 16 seconds.

Gracie Muehlberger, 15, and Dominic Blackwell, 14, were killed during the shooting. Three others were injured and are expected to survive.

Berhow carried out the shooting on his birthday. Investigators say there is no clear motive for the shooting. They have not found a manifesto, diary or suicide note.

Investigators say they think Berhow planned the school shooting but shot students at random.

It wasnt a spur-of-the-moment act, Los Angeles County Sheriff Alex Villanueva said at a news conference Friday.

Villanueva said that Berhow appeared to have experience with the firearm he used in the attack. The student was able to continue shooting students even after the gun initially malfunctioned.

Officials do not know how Berhow obtained the gun or where it originated. Berhows deceased father had owned six guns, though none of those firearms were used in the shooting, according to Villanueva. Investigators also uncovered several unregistered firearms at Berhows residence.

The gun found at the school is being analyzed in a crime lab.

The school district has faced shooting threats before. In September, six students in the William S. Hart Union School District, which includes Saugus High, were arrested for making violent school threats on social media.

This article has been updated with information from a Friday news conference.